This invention relates to a novel process for the preparation of 13.beta.-alkyl-4-gonene-3,17-diones of the general Formula I ##STR2## wherein R.sub.1 is methyl or ethyl.
The 13.beta.-alkyl-4-gonene-3,17-diones of general Formula I are known. These compounds are valuable intermediates for the preparation of pharmacologically effective steroids. They are utilized, for example, as starting materials for the synthesis of 17.beta.-hydroxy-17.alpha.-ethynyl-13.beta.-alkyl-4-gonen-3-ones and the corresponding esters which, are the active agents of oral contraceptives. See Annalen 702, 141 [1967], J. Chem. Soc. [1964], 4472.
Processes for the total synthetic production of 13.beta.-alkyl-4-gonene-3,17-diones of general Formula I include those set forth in J. Org. Chem. 38, 3244 [1972] and J. Org. Chem. 37, 3385 [1972].
However, these conventional processes are very expensive, because numerous reaction steps are required for the total synthesis of these compounds, individual reaction steps can be conducted only at considerable technical expense, and the overall combined yields thus obtained are often unsatisfactorily low.
It is an object of this invention to provide a process for the total synthesis of 13.beta.-alkyl-4-gonene-3,17-diones in a simpler manner than heretofore possible. It is a further object of this invention to provide a stereoselective synthesis of a perhydroindane intermediate having a trans-junction between the five- and six-membered rings by catalytic hydrogenation of a precursor 5,6,7,7a-tetrahydroindance compound. Other objects will become apparent to those skilled in the act.